• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.5
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• pp.380-388
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• 2017

The services of the IoT environment should constantly collect situation information, and perform appropriate actions according to the situation. Therefore, there is a need for a method that can express collected situation information. In this paper, we propose a situation information model based on ontology for IoT environment. Since the proposed model is ontology based, it supports semantic interoperability. We also build an upper-level ontology to model common situation information of various IoT domains. It is easy to understand and use because it expresses situation information consistently by expressing person, environment, and thing constituting IoT environment as class and defining properties indicating the situation. In addition, since the situation information need to reflect dynamic situation, it has a feature to model the creation time and the life time of the situation information so as to judge the validity of the information. The proposed ontology model is described using OWL, and the service can be described based on the constructed ontology.

• Journal of the Korean Society for information Management
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• v.18 no.3
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• pp.87-114
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• 2001

A hybrid information environment can be described as one where an appropriate range of heterogeneous information services is presented to the user in a consistent and integrated way via a single interface. The purpose of this study is to suggest a need of hybrid information services through understanding of the hybrid information environment and hybrid library. Additionally, this study deal with basic concepts of design for a hybrid information service model and address a number of hybrid library projects based on these concepts, such as Agora, BUILDER, HealdLine, HyLife, and MALIBU. Finally, this study survey generic a model of hybrid library and suggest basic principles for building of hybrid information service model, such as integration, seamlessness, authentication, interconnectivity, and personalization of information seeking process environment.

• Journal of Korea Water Resources Association
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• v.51 no.3
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• pp.273-280
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• 2018

Accurate estimation of evapotranspiration is mightily important for understanding and analyzing the hydrological cycle. There are various methods for estimating evapotranspiration and each method has its own advantages and limitations. Therefore, it is necessary to develop an optimal evapotranspiration product by combing different evapotranspiration products. In this study, we developed an optimal evapotranspiration by fusing two satellite- and model-based evapotranspiration estimates, including revised remote sensing-based Penman-Monteith (RS-PM) and Modified Satellite-Based Priestley-Taylor (MS-PT) methods, Global Land Data Assimilation System (GLDAS), and Global Land Evaporation Amsterdam Model (GLEAM). The statistical analysis (i.e., correlation coefficients, index of agreement, MAE, and RMSE) of combined evapotranspiration product showed to be improved compared to the individual model results. After confirming the overall results, in future studies, advanced data fusion techniques will be used to obtained improved results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.590-593
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• 2009

To identify the detailed 3D flow characteristics of a model scramjet engine, a unified 3D numerical analysis was performed. The numerical domain of concern includes the entire flow path of the model scramjet engine extending from the intake to the nozzle exhaust. Turbulent models($k-{\omega}$ SST and low Reynolds number k-e with Sarkar model) were applied with comparison of experiment result. Intake side wall's effect on flow characteristics was analyzed in view points of flow quality at inlet duct and near the flame holder as well. The code is paralleled with multi-block feature using MPI(Massage Passing Interface) library to speed up the 3D calculation.

• The Journal of Korean Association of Computer Education
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• v.14 no.1
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• pp.159-168
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• 2011

This study analyzed whether the ontology-based information-searching model affected the ability of students to effectively search for meaningful information to carry out their projects. The experiment results illustrated that the amount of relevant information sought by the ontology-based information retrieval (OIR) method was significantly greater than that of the existing information retrieval (EIR) method. In addition, the relevance rate of the bookmarked documents sought by the OIR method was significantly greater than that of the EIR method. Interviews showed that the OIR model was helpful for students to effectively find information and thus, it helped them to complete the project more easily. Furthermore, the OIR model was beneficial for them to understand the subordinate concepts and their relationships for an important learning concept. The results of this study indicate that the OIR model could be used as a supplementary learning tool for project-based learning.

• Journal of the Society of Disaster Information
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• v.12 no.4
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• pp.329-341
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• 2016

The social crisis like swine flue epidemics can influence on the various groups and organizations in society. The activity and result by the influence can be different according to the kind of social crises and characteristics of organizations. To understand the short-term response of an organization to social crisis, ser-M model has not been used, but in this study, it is shown that the study using ser-M model can be applicable to short-term event and that ser-M model can be one of access methods to social crisis and disaster. In this study author tried to examinate the response of an hospital in Korea to swine flue epidemics from 2009 to 2010 based on ser-M model. This ser-M model can be used for analysis of response by an organization or a company to short-term external environmental impact like social crisis or disaster as well as long-term management strategy.

• Journal of the Korean Vacuum Society
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• v.19 no.1
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• pp.72-80
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• 2010

It is very important to predict and analyze the change of voltage and current distribution of current strap, abnormal voltage distribution of transmission line and resonance phenomenon by coupling between current straps for more stable operation of ICRF system. In this study, to understand those phenomena by coupling, 8-port coupled transmission line model is completed by appling S-parameter measured in the prototype KSTAR ICRF antenna to the model. The determined self-inductance, mutual-inductance and capacitance of antenna straps are shown to be lower than that calculated from 2D approximate model due to finite length of strap. The coupled transmission line model of current strap will be utilized to the operation of ICRF system of KSTAR in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.755-761
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• 2014

Internal or external restraint of concrete strain due to drying shrinkage and creep in concrete structures causes mechanical strain and becomes a source of persistent change in creep-causing stress conditions. Mathematical modeling to incorporate the persistent change of creep-inducing stress is generally achieved with consideration of the ages of concrete and concrete properties at the times of loadings, and stress history. This paper presents an incremental format of creep model based on parallel creep concept to depict the creep under time-varying stress history in developing creep strain. Laboratory experiments are carried out to validate the performance of the presented creep model. Typical creep phenomena are addressed through the comparisons between the measured and predicted creep strains.

• The Journal of the Korea Contents Association
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• v.7 no.6
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• pp.22-30
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• 2007

Most real word systems such as world economy, stock market, and medical applications, contain a series of dynamic and complex phenomena. One of common methods to understand these systems is to build a model and analyze the behavior of the system. In this paper, we investigated methods for best clustering over time series data. As a first step for clustering, BIC (Bayesian Information Criterion) approximation is used to determine the number of clusters. A search technique to improve clustering efficiency is also suggested by analyzing the relationship between data size and BIC values. For clustering, two methods, model-based and similarity based methods, are analyzed and compared. A number of experiments have been performed to check its validity using real data(stock price). BIC approximation measure has been confirmed that it suggests best number of clusters through experiments provided that the number of data is relatively large. It is also confirmed that the model-based clustering produces more reliable clustering than similarity based ones.

• The Journal of the Korea Contents Association
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• v.13 no.4
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• pp.53-63
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• 2013

This paper presents an importance sampling(IS) embedded experimental frame(EF) design for efficient Monte Carlo (MC) simulation. To achieve IS principles, the proposed EF contains two embedded sub-models, which are classified into Importance Sampler(IS) and Bias Compensator(BC) models. The IS and BC models stand between the existing system model and EF, which leads to enhancement of model reusability. Furthermore, the proposed EF enables to achieve fast stochastic simulation as compared with the crude MC technique. From the abstract two case studies with the utilization of the proposed EF, we can gain interesting experimental results regarding remarkable enhancement of simulation performance. Finally, we expect that this work will serve various content areas for enhancing simulation performance, and besides, it will be utilized as a tool to understand and analyze social phenomena.